Our long-term objective is to develop a physiological model to study placebo effects in Parkinson's disease (PD). Our immediate objective is to use force decline rate and motor evoked potential (MEP) amplitudes during intermittent exercise to examine how expectancy and personality affect responses to placebo levodopa and sham acupuncture in PD in two parallel but independent studies. Study I. Placebo levodopa. Hypothesis IA: Higher expectancy will reduce force decline rates or MEP facilitation from intermittent exercise in PD after placebo levodopa. Specific Aim IA: To examine expectancy effects after placebo levodopa. Sixty subjects will perform two sets of intermittent exercises 30 minutes apart at Visit 1. At visit 2, they will be randomly assigned to one of three groups. Every subject will receive placebo dissolved in KooI-Aid. Group 1. Full Expectancy. Subjects told they will receive real levodopa. Group 2. Half expectancy. Subjects told they have a 50% chance of real levodopa or placebo. Group 3. No expectancy. Subjects will be told they will not receive levodopa. Hypothesis IB: PD subjects with stronger 'novelty-seeking' personalities experience greater response to placebo levodopa. Specific Aim IB: To examine the relationship between personality, force decline rate, and MEP facilitation. Study II. Sham acupuncture. Hypothesis IIA: Higher expectancy will reduce rate of force decline or MEP facilitation in the l intermittent exercise protocol when the subjects receive sham acupuncture. Specific Aim IIA: To examine expectancy effects after sham acupuncture. The design is the same as Specific Aim IA. For the visit 2, all sixty subjects will receive sham acupuncture and they will be told they are receiving real acupuncture (Group 1, full expectancy), 50% chance of real or sham acupuncture (Group 2, Half expectancy), or sham acupuncture (Group 3, No expectancy). Hypothesis lIB: PD subjects with stronger 'novelty-seeking' personalities will experience greater response to sham acupuncture. Specific Aim lIB: To examine the relationship between personality force decline rate, and MEP facilitation. Subjects in both studies will fill out questionnaires evaluating personality including NEO-Five-Factor Inventory (NEO-FFI). We will evaluate primary outcome measures including force decline rates and MEP facilitation during intermittent exercise before and after placebo levodopa or sham acupuncture in all 3 groups in both studies. We will examine the relationships between personality and outcome measures.